How to Add Links to External Pages in Main Site Menu
To add external page links to your main site menu, navigate to Site Builder and click Customize.
From there click on the Navigation tab.
Now click on the New Item button.
The left column will load options to manage the new menu item. Click on the Link Type dropdown menu and select External Link. Proceed by placing the link to the external site in the External Link field and set a menu item name which will be displayed in your menu. And finally, make sure you are adding the link to the Main Navigation on top of the site from the Location dropdown.
